It could be possible to have high GDP with low paychecks… it basically means the entire economy mostly consists of the wealthy few buying and selling things to each other. It is easy to see how that could happen if more things become automated.
You could imagine a world where there are only two people who own anything, and the entire economic productivity is generated by robots owned by those two people creating things and selling them to the other person, who uses those things for their robots to work with. You could produce tons and tons of things with no workers, and the GDP would keep growing.
Of course, the high GDP doesn’t mean everyone is fed and sheltered. Having a functioning and growing economic market is required for capitalism to serve its purpose of providing for the citizens, but it isn’t the ONLY requirement. If the form capitalism takes as we move into the future is one that stops providing for enough of its citizens, it won’t be able to sustain itself. I think there are things we can do to shift our capitalism to do a better job of providing for everyone, but there are a lot of forces fighting against that.